Patients who undergo selective dorsal rhizotomy (SDR) surgery at St. Louis Children’s Hospital’s Center for Cerebral Palsy Spasticity often need an additional surgical procedure for muscle/tendon lengthening to relieve contractures (limited motion) in their joints. Although SDR relieves spasticity, the contractures that remain require lengthening. The goal of surgery is to increase your child’s range of motion, allowing them to walk with heels on the floor and knees straight.

An orthopedic surgeon uses minimally-invasive surgical procedures to accomplish the lengthenings. This allows the muscle to return to a normal length and the joint to straighten, and is one step in helping children walk with their heels on the floor and knees straight.

Unlike other surgical approaches to tendon lengthening, the minimally-invasive procedure allows for a quicker recovery and in most cases, children start therapy the very next day. Smaller incisions lead to less pain, shorter surgery times and a decreased chance of complications. Depending on the muscle or tendon lengthened the child may or may not require casting. Achilles tendon lengthening does require below the knee leg casts for a short time. Ambulation is allowed and therapy continues while the casts are on. Hamstring lengthenings and gastroc recessions do not require casts. If braces are not immediately available after gastroc recession, temporary casts may be placed to provide support and limit motion until the braces are ready. The duration of casting varies with individual circumstances. Patients in the country for a limited time will have their casts removed to allow for three days of PT in braces before departure. Everyone else will keep their casts 3-4 weeks.

Muscle/Tendon Lengthening Procedure

This surgery is accomplished using a minimally invasive approach for controlled lengthening. The hamstring tendons, gastroc muscle and heel cord (Achilles tendon) are the most common structures that require lengthening. The procedure is performed in an operating room under general anesthesia. A minimally invasive feathering technique is used to lengthen the tendon as opposed to the traditional method of cutting and reattaching the tendon. Hamstrings can be lengthened medially (inner knee) or laterally (outside knee). The majority of the time only the medial hamstring needs to be lengthened through an incision that is less than an inch long. A Gastroc Recession involves releasing the sheath over the gastroc muscle, again through an incision less than an inch long on the back of the calf. The Achilles tendon is lengthened through 3 tiny incisions on the back of the heel, each only requiring one stitch.

Patients spend one night in the hospital to monitor and control any post-op pain and nausea and to receive antibiotics. For those participating in the SDR/Perc program, the PT schedule resumes the next day. PT will come to the bedside for everyone else to make sure your child is comfortable walking in the casts/braces. Unlike SDR, there is no epidural catheter or catheter in the bladder. Your child will wake up with an IV and casts in place. Children will be able to choose the color of their casts. The casts can be removed at a facility near your home if you are not planning on being in St. Louis for the cast removal.

Physical Therapy

Children who undergo either the selective dorsal rhizotomy surgery alone or in combination with follow-up tendon lengthening may experience rapid and dramatic changes in their walking. To enhance their recovery and improvement, we recommend physical therapy (PT) four to five times a week for the first six months; three to four times per week for the next six months; and two to four times a week for the following year or longer. The intense PT schedule helps children maintain their motion and their maximum strength and walking potential. If your child’s SDR was greater than a year ago, PT will need to ramp back up to 4-5 times a week for about 3 months, then can incrementally decrease over time as strength returns.

A specially-trained pediatric physical therapist will work with your child while they are at the hospital, and create an individualized plan to continue the therapy once they return home.

Information is available for your formal local PT and for you to use at home as parents.


Bracing is an integral part of maintaining the correction achieved with surgery. Dr. Park prefers the Cascade Turbo bracing system that consists of both tall and short bracing. We can provide a prescription for these to be measured prior to the procedure or you can have them made in St. Louis if you will be here when the casts come off. If you are part of the SDR/Percs package your bracing needs will be determined and ordered by the team. The majority of Orthotists will not deliver and fit braces that have been molded elsewhere, so it is important to have braces molded and a plan for delivery and fitting in place before surgery for percs. PLEASE contact our office if you did not receive a prescription or have bracing measured prior to scheduling the procedure.

Bracing Schedule

After heel cord/gastroc lengthening surgery, your child will wear the full Turbo brace to assist with walking for 6-8 weeks. As your child gets stronger, he or she may transition to a less restrictive splint such as the SMO that is inside the Turbo brace for another 6-8 weeks. At some point, Chipmunk type shoe inserts may be used following bracing. Physical therapy will assist in the timing to downsize the braces. Night time dorsiflexion stretching splints are worn until the patient grows out of them. After hamstring lengthening surgery, your child will wear nighttime knee immobilizers to maintain correction.

Eligibility for Surgery

T.S. Park, MD, pediatric neurosurgeon, and the pediatric orthopedic team will evaluate a patient’s eligibility for the tendon lengthening surgery. If your child is a candidate for tendon lengthening, timing is variable. International patients, in the country for a limited amount of time, can be done 10-14 days post SDR. Domestic patients can be done as soon as 2-4 months after SDR as recommended by Dr. Park. We will schedule an evaluation with surgery the following day for our out of town patients and can often coordinate with a post SDR visit with Dr. Park.


For more information on the cerebral palsy treatment team at St. Louis Children's Hospital, call us at 314.454.KIDS (5437) or 800.678.KIDS (5437) or email us to request an appointment.